The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Harrison Weinerman:
Photography might come easy to some people, but for some, its just plain pain! In this app, learn strategies, and information like the pros do! All made extremely easy to follow. Lets say you need to lookup a quick definition, open the app and tap "Quick Definitions"! Its that simple! The subjects in this app include:
DSLR vs. Point and Shoot
Quick Definitions... AND MORE! And one of the biggest points of this app, is that it was: coded by, written by, and made by a 12 year old kid!' So go out and buy this app! (Notes: To take full advantage of this app you should have a camera, and some tutorials require a camera with a manual mode.)